NAME: _________________________
BI 112 Pre-Lab #10: Genetics
The goal with this assignment is for you to gain an understanding of how to perform the Punnettsquare method and to understand its application. Please take time to read Chapter 9 in your text
for an understanding of the vocabulary and the process.
Also, be aware that when you are calculating probabilities, they range from 0 – 1. Thus, if
there’s a 50% chance of an event occurring, it has a probability of 0.5.
1. Hemoglobin is an important protein in red blood cells. It functions to carry oxygen from the
lungs to the tissues of the body. Sickle cell anemia is a recessive trait that results from a
single base substitution. When an individual has two copies of the sickle allele, they will be
affected with anemia (low number of functioning red blood cells). “S” represents the normal
allele for hemoglobin. “s” represents the sickle allele for hemoglobin.
Answer the following questions about a cross (mating) between a father who is “ss” and a
mother who is “Ss”.
What are the potential gametes produced by the father? _________________
What are the potential gametes produced by the mother? _________________
Complete a Punnett-square for a cross between these two individuals.
Provide the probability of each of the following genotypes:
SS _________________
Ss _________________
ss _________________
Provide the probability of each of the following phenotypes:
Sickle cell anemia _________________
Non-sickle cell anemia _________________
NAME: _________________________
2. Some individuals are born with 6 fingers on each hand. This condition, called “polydactyl”
is due to a dominant allele. “P” represents the polydactyly allelle. “p” represents the normal
allele.
Answer the following questions about a cross between a father who is “Pp” and a mother who is
“Pp”.
What are the potential gametes produced by the father? _________________
What are the potential gametes produced by the mother? _________________
Complete a Punnett-square for a cross between these two individuals.
Provide the probability of each of the following genotypes:
PP _________________
Pp _________________
pp _________________
Provide the probability of each of the following phenotypes:
Polydactyly _________________
Non-polydactyly _________________